Plasma levels of lidocaine, o-toluidine, and prilocaine after application of 8.5 g Oraqix in patients with generalized periodontitis: effect on blood methemoglobin and tolerability.

Oraqix, a novel non-injectable anesthetic gel containing lidocaine and prilocaine and a thermosetting agent has been developed to provide localized anesthesia in periodontal pockets during scaling/root planing (SRP). The aim of this open study was to determine the plasma levels of lidocaine and prilocaine following application of 8.5 g Oraqix (5 cartridges) to 11 patients with generalized periodontitis (> or = 49% of tooth pockets > or = 5 mm and > or = 23% of pockets > or = 6 mm). Oraqix was applied to the pockets during periodontal probing and SRP over a 2.6 3.4 h period. Blood samples were collected up to 10 h after the start of application of Oraqix. Peak plasma levels of lidocaine (0.16-0.55 mg/L) and prilocaine (0.05-0.18 mg/L) occurred 2.0-3.7 h and 2.0-3.3 h, respectively, after the start of application of Oraqix. These levels are well below threshold levels for initial signs of central nervous system (CNS) toxicity. In conclusion, application of 8.5 g Oraqix (212.5 mg of lidocaine base and 212.5 mg of prilocaine base) in periodontal pockets was well tolerated and displayed a wide safety margin with respect to plasma levels normally associated with systemic toxicity.